With the development of Internet technologies, the Internet applications have also been developed rapidly. The Internet applications may include but are not limited to instant messaging applications, SNS (Social Networking Services) applications, voice communication applications, etc. The Internet applications described above may be installed in terminal such as note-book computers, mobile phones, PAD (tablet computers). An end-user may use an Internet application in the terminal to make an audio call such as a voice call, an audio chat with another user. The audio quality is an important factor for the audio calls. Therefore how to improve the audio quality of audio calls is an issue to be settled.